ipribadi wrote:I don't think performance (both acceleration & mpg) would have gained alot using a 6AT.
The price with a 6AT would probably have to be hiked by $500 or so.

Wrong. I can't speak on price, but certainly on performance and fuel economy. People complain about lack of torque despite of horsepower because of taller ratios that Honda chooses. RL, MDX and RDX are perfect examples. TSX will benefit a lot in performance by having shorter low gears.

Having 5AT limits that. As it is now, the gear span for the 5AT in TSX is 4.69 (Gear Span = first gear ratio divided by top gear ratio). A 6AT can provide gear span around 6.00 which is the greatest advantage a CVT provides as well. What does it mean?

With a 6AT, TSX could use up to 27% shorter first gear ratio and still be able to maintain the same top gear. In terms of sheer numbers, the maximum thrust generated in first gear would be comparable to the existing 5AT mated to an engine producing 218 lb-ft (as opposed to 172 lb-ft).

But, not all of 27% needs to go towards lower gears. Such 6AT could allow shortening of lower gears by about 20%, and still leave room for a top gear that is 9-10% taller. So, instead of cruising at 2200 rpm in top gear at 60 mph, the revs will be around 2000 rpm... improved mileage.

This is exactly how BMW provides folks the feeling of having stronger horses (and lately, Lexus) and reaps the benefits. To put it all in perspective, consider these (over all gear ratios in first and top gear) with BMW 328i's numbers in parenthesis...
2009 TSX
First Gear: 11.77
Top Gear: 2.51

2008 328i
First Gear: 15.18
Top Gear: 2.499

The top gear in the BMW is slightly taller but the first gear is 29% shorter! And shorter gear = greater thrust from same torque.

That's definitely true. It would be nice if Honda brings out 6AT or even 7AT soon. But I can understand why there's a delay - they rushed and brought the 5AT in the market many years ago, and its reliability was questionable. I guess Honda doesn't want to repeat that again. Afterall, Honda is renowned for its reliability, it can't afford to screw up again.

The TSX's 5th gear is probably right where it should be; achieving good mpg with minimal downshift during hwy cruise load variations.

So the 6AT would improve acceleration only.

With >85% of it's torque available between 3500 - 5800 rpm, the engine's mid range punch is good.
I don't think this TSX engine would feel as "peaky" as typical Honda 4cyl's do. Peaky engine's benefit the most from close ratio gearing.

For the TSX w/ auto tranny's target market, the new engine's characteristics, cost and reli benefits of the 5AT, I would tend to agree with Honda with the decision to keep the 5AT.

No. It should improve fuel economy too, and I'm not talking just EPA rating (which seems to help in marketing).

The top gear in TSX could be taller but likely being limited by the 5AT. Making it any taller will compromise lower gears which will either have to be taller or the spacing between gears becomes large (a documented issue with RL).

For a perspective, Civic/5AT is designed to cruise with a leisurely 1900 rpm at 60 mph, while TSX will be doing so at 2200 rpm.

Properly selected ratios for 6AT (BMW and Lexus*) can do wonders to fuel economy and, more importantly in this class, performance. What must be avoided is GM/Mercedes approach where the top gear is way too tall that it becomes a nuisance (7AT in case of Mercedes). But that is happening because they started with taller ratios for lower gears.

* I ignored Toyota since the FWD/6AT used in Camry/Avalon/Sienna/Highlander/ES350 isn't quite on par with the Lexus (IS/GS) version but that may also be because it is used on front drivers with V6 that has good torque output... a Lexus-like 6AT will make for an interesting tug of war between the driver and the Toyotas (and ES350).

No. It should improve fuel economy too, and I'm not talking just EPA rating (which seems to help in marketing).

The top gear in TSX could be taller but likely being limited by the 5AT. Making it any taller will compromise lower gears which will either have to be taller or the spacing between gears becomes large (a documented issue with RL).

For a perspective, Civic/5AT is designed to cruise with a leisurely 1900 rpm at 60 mph, while TSX will be doing so at 2200 rpm.

Properly selected ratios for 6AT (BMW and Lexus*) can do wonders to fuel economy and, more importantly in this class, performance. What must be avoided is GM/Mercedes approach where the top gear is way too tall that it becomes a nuisance (7AT in case of Mercedes). But that is happening because they started with taller ratios for lower gears.

* I ignored Toyota since the FWD/6AT used in Camry/Avalon/Sienna/Highlander/ES350 isn't quite on par with the Lexus (IS/GS) version but that may also be because it is used on front drivers with V6 that has good torque output... a Lexus-like 6AT will make for an interesting tug of war between the driver and the Toyotas (and ES350).

No. It should improve fuel economy too, and I'm not talking just EPA rating (which seems to help in marketing).

The top gear in TSX could be taller but likely being limited by the 5AT. Making it any taller will compromise lower gears which will either have to be taller or the spacing between gears becomes large (a documented issue with RL).

For a perspective, Civic/5AT is designed to cruise with a leisurely 1900 rpm at 60 mph, while TSX will be doing so at 2200 rpm.

Properly selected ratios for 6AT (BMW and Lexus*) can do wonders to fuel economy and, more importantly in this class, performance. What must be avoided is GM/Mercedes approach where the top gear is way too tall that it becomes a nuisance (7AT in case of Mercedes). But that is happening because they started with taller ratios for lower gears.

* I ignored Toyota since the FWD/6AT used in Camry/Avalon/Sienna/Highlander/ES350 isn't quite on par with the Lexus (IS/GS) version but that may also be because it is used on front drivers with V6 that has good torque output... a Lexus-like 6AT will make for an interesting tug of war between the driver and the Toyotas (and ES350).

No. It should improve fuel economy too, and I'm not talking just EPA rating (which seems to help in marketing).

The top gear in TSX could be taller but likely being limited by the 5AT. Making it any taller will compromise lower gears which will either have to be taller or the spacing between gears becomes large (a documented issue with RL).

For a perspective, Civic/5AT is designed to cruise with a leisurely 1900 rpm at 60 mph, while TSX will be doing so at 2200 rpm.

Properly selected ratios for 6AT (BMW and Lexus*) can do wonders to fuel economy and, more importantly in this class, performance. What must be avoided is GM/Mercedes approach where the top gear is way too tall that it becomes a nuisance (7AT in case of Mercedes). But that is happening because they started with taller ratios for lower gears.

* I ignored Toyota since the FWD/6AT used in Camry/Avalon/Sienna/Highlander/ES350 isn't quite on par with the Lexus (IS/GS) version but that may also be because it is used on front drivers with V6 that has good torque output... a Lexus-like 6AT will make for an interesting tug of war between the driver and the Toyotas (and ES350).

Note: Highlander and Sienna only offer 5AT.

Thanks! I thought RX350 was the only one left.

as for the 5AT vs 6AT argument, seriously, the '09 TSX does pretty well with the 5AT. There are a half dozen other Hondas and Acuras that would benefit FAR MORE than the TSX by the fitment of a 6AT. The torque delivery is so robust with this K24, even with the 5AT's relatively widely spaced gear ratios, the car never feels like it's caught in a hole between ratios. Accord V6, Acura RL, Acura MDX, ... yes, 6AT please!

Jeff wrote:as for the 5AT vs 6AT argument, seriously, the '09 TSX does pretty well with the 5AT. There are a half dozen other Hondas and Acuras that would benefit FAR MORE than the TSX by the fitment of a 6AT. The torque delivery is so robust with this K24, even with the 5AT's relatively widely spaced gear ratios, the car never feels like it's caught in a hole between ratios. Accord V6, Acura RL, Acura MDX, ... yes, 6AT please!

Jeff wrote:as for the 5AT vs 6AT argument, seriously, the '09 TSX does pretty well with the 5AT. There are a half dozen other Hondas and Acuras that would benefit FAR MORE than the TSX by the fitment of a 6AT. The torque delivery is so robust with this K24, even with the 5AT's relatively widely spaced gear ratios, the car never feels like it's caught in a hole between ratios. Accord V6, Acura RL, Acura MDX, ... yes, 6AT please!

Does '09 feel that much stronger than '08 (with AT)?

I wouldn't say it feels stronger, simply because of the '09's extra weight. But based upon my (brief) experience in a 5AT TSX, unlike some other Hondas and Acuras I didn't feel like the 5AT was a key obstacle to extracting the most performance from the vehicle.

Isn't that for the V6 5AT models only? I have a TL-S and you are right on with the 3rd gear getting up to 105-110mph, 2nd gear it was more like 70mph for me. 4th gear is a joke, it's already an overdrive gear. I have also driven the TSX 5AT before, and I think the gears were a bit shorter.

That is based on assumption that each gear will allow hitting redline, and in case of Honda's 5AT that almost never happens. Lower gears are often limited to 5800 rpm, which takes me to your observations on the Accord.

Accord V6 has 6800 rpm redline and likely uses gear ratios almost identical (if not same) as this TSX. So, your observation is in-line with my calculation, except that the top speed you're noting in lower gears happen to be at 5800 rpm. Here's how maximum speed in TSX would look in each lower gear limited to just 5800 rpm...
1: 39 mph
2: 65 mph
3: 97 mph

The problem is that this actually hurts performance (0-60 as well as quarter mile) since the car is unable to use the maximum power which happens to be sitting at 7000 rpm. In other words, the 5AT is "short shifting".

This is also a problem in current Accord V6/5AT. In a 0-60 run, the Accord isn't taking advantage of its rated maximum power. The maximum power only shows up in highway passing situation (higher gears).

- With 5AT, the TSX is rated with peak torque of 170 lb-ft @ 4300 rpm (compared to 172 lb-ft @ 4400 rpm for 6MT). It suggests a slightly more aggressive low-end tuning with the 5AT (doesn't necessarily show up in the specified peak rating or where the peak happens).

- Maximum thrust calculated (assuming 3650 lb laden weight, 10% drive train loss) is somewhat disappointing with 5AT, at 0.43g (By comparison, IIRC, 2003 Accord V6 had it at about 0.55g, almost 25% better). And this is where the need for 6AT creeps in (along the lines I suggested earlier). Acura could have made the drive train feel like V6 and yet manage taller ratios for taller gears for fuel economy. This is where 5AT's limitation shows up.

By comparison, TSX/6MT's calculated max thrust is about 0.57g and that leaves little room to complain about, and typical of Honda/Acura. The 6MT's are almost always tuned to provide the effect that 5AT version sorely lacks.

Wizard wrote: Lower gears are often limited to 5800 rpm, which takes me to your observations on the Accord.

Accord V6 has 6800 rpm redline and likely uses gear ratios almost identical (if not same) as this TSX. So, your observation is in-line with my calculation, except that the top speed you're noting in lower gears happen to be at 5800 rpm. Here's how maximum speed in TSX would look in each lower gear limited to just 5800 rpm...

The '09 TSX has a spec'd redline at 7,100 RPM.
I really don't believe a Honda 5AT would shift 1300 RPM below redline.

I can assure you that not all Honda/Acura 5AT's shift at 5800rpm. I floor my car once in a while in normal AT mode (non-sportshift mode) and it will hit at least 6500rpm (6900rpm redline) before shifting up but rarely go up to the redline (ie, it will shift between 6500 - 6900rpm). If I use sportshift mode then it will even bounce off the rev limiter at over 7000rpm, which is past the redline.

I worked at a Honda dealership and I floored it a few times on several Civics and Accords with 5AT and they all would hit close to the redline (over 6000rpm) in normal mode (not gate shifting).

I guess by "often limited to 5800rpm," that would be true if you don't floor it.

Going by your numbers, and assuming the same gearing as the '08 Accord EX, the '09 TSX would cruise at 1929 rpm @60mph, and we both know that ain't true.

The gear ratios for the '04 TSX are exactly the same for the '08 Accord EX except for the 2nd gear and the Accord has a slightly larger tire (by 1.5%, which is the same size for the '09 TSX)

It is based on simple math, using tire size, redline and overall drive ratios from specs on hondanews. And yes, the same math suggests TSX will cruise at 1958 rpm @ 60 mph (although I had read somewhere that it is 2200 rpm... not sure where). And ~2000 rpm might be it.

~45 mph in first, ~75 mph in second and ~110 mph in third is typical of most Honda AT gearing (even applies to my 1998 Accord).

Numbers on R&T for RDX suggest that it may not be limited to 5800 rpm in lower gears, and the numbers they quote at its redline (6800 rpm) is also close to the typical (44/73/110/130*/130*).

With 6,600rpm shifts, 2nd is 68.5mph and 3rd is 102mph.
Now that's not too good.
That's too tall, but at least the RPM never drops below 4000 rpm and there's a pretty good surge of torque at 4000 rpm.

you can take it right to the limiter with the sportshift, and it seems like even in full auto mode, it was upshifting damn close to redline, if not the limiter. 4000 rpms on this motor is nearly where the torque peaking, and it starts pulling the hardest between around 4000 and 6000 rpms, tapering off mildly from 6000 to redline.

ipribadi wrote:That's too tall, but at least the RPM never drops below 4000 rpm and there's a pretty good surge of torque at 4000 rpm.

That is typical of Honda/Acura approach to gearing with AT. The only exception is the RL.

I was fully expecting Acura to go with 6AT when 2005 RL arrived. Instead, a short cut was taken. Although, 2005+ RL has a 5AT, it was given a near 6AT-like span of about 5.6:1 (which is actually better than Toyota/Lexus FWD 6AT's 5.4:1).

It starts out with one of the most aggressive first gear for an AT in Honda/Acura's history with overall drive ratio of about 12.40:1, but with only five gears to play with, to ensure a very tall top gear (it is impressive with overall drive ratio of 2.21:1), the middle gears ended up being widely spaced out.

For MDX, Acura pulled back the aggressiveness at both ends, since it was still going to stick with 5AT. It is about time! Shape of torque curve matters little when gearing isn't right. All it does is provide impression of being "soft" and performance resting only when once rolling. Why not both?

ipribadi wrote:It's just weird, for the 5AT they made the 4th gear taller (.694) than what the '08 Accord EX (4cyl) has (.773)...

...Why on earth would they do this is beyond me.

Taller fourth is unlikely to hurt performance. In fact, it may be a good thing for fuel economy since, as I have mentioned elsewhere (and probably in this thread) that under 45 mph, Honda/Acura chooses to run the vehicle in fourth gear (in 5AT set up). For highway performance, third gear is more important, since fourth would be skipped anyway (unless accelerating mildly... in which case performance won't be a priority anyway).